M AY 2015, N O 16
ISOPTWPO Today
BIOGRAPHY Dr.KATHRYN D. SULLIVAN was one of the six women (in a class of 35) selected in 1978 to be Space Shuttle astronauts, and she was the third woman tapped to fly. An Earth scientist and PhD. geologist/oceanographer, mission specialist Sullivan was a good match for the STS-41G mission, which carried an Earth-observation payload and deployed the Earth Radiation Budget Satellite. She was co-investigator for the Shuttle Imaging Radar (SIR-B) remote sensing experiment and actively involved in research use of the Large Format Camera and other instruments mounted in the payload bay. Most of Dr. Sullivan’s efforts prior to joining NASA were concentrated in academic study and research. She was an earth sciences major at the University of California, Santa Cruz and spent 1971-1972 as an exchange student at the University of Bergen, Norway. Her bachelor’s degree (with honors) was awarded in 1973.
Her doctoral studies at Dalhousie University included participation in a variety of oceanographic expeditions, under the auspices of the U.S. Geological Survey, Wood’s Hole Oceanographic Institute and the Bedford Institute. Her research included the Mid-Atlantic Ridge, the Newfoundland Basin and fault zones off the Southern California Coast. She is a private pilot, rated in powered and glider aircraft. The first American woman to walk in space, Dr. Sullivan is a veteran of three shuttle missions and a 2004 inductee to the Astronaut Hall of Fame. In 1993, Dr. Sullivan left NASA to accept a Presidential appointment to the post of Chief Scientist at the National Oceanic and Atmospheric Administration (NOAA). Here she oversaw a wide array of research and technology programs ranging from climate and global change to satellites and marine biodiversity. From 1996 to 2006, Dr. Sullivan served as President and CEO of COSI (Center of Science & Industry) in Columbus, Ohio. Under her leadership, COSI strengthened its impact on science teaching in the classroom and its national reputation as an innovator of hands-on, inquiry-based science learning resources. Dr. Sullivan then served as the inaugural Director of the Battelle Center for Mathematics and Science Education Policy in the John Glenn School of Public Affairs at The Ohio State University. Dr. Kathryn Sullivan was confirmed by the Senate as the Under Secretary of Commerce for Oceans and Atmosphere and NOAA Administrator on March 6, 2014, having served as Acting NOAA Administrator since February 28, 2013. Astronaut Biographical Data — Image Credit:NASA
Editorial Dear Reader It is my pleasure to introduce the ISOPTWPO. ISOPTWPO(International Space Flight & Operations - Personnel Recruitment, Training, Welfare, Protocol Programs Office) is part of ISA, which support research on Human Space Flight and its complications. The International Space Agency (ISA) was founded by Mr. Rick Dobson, Jr., a U.S. Navy Veteran, and established as a non-profit corporation for the purpose of advancing Man’s visionary quest to journey to other planets and the stars. ISOPTWPO will research on NASA’S Human Research Roadmap. It will also research on long duration spaceflight and publish special issues on one year mission at ISS and twin study. Mr. Martin Cabaniss
Director: Mr. Martin Cabaniss ISOPTWPO – International Space Agency(ISA) http: // www. international-space-agency. us/ martin.cabaniss@international-space-agency.us
IN THIS EDITION
Acute - 8: How can Probabilistic risk assessment be applied to SPE risk evaluations for EVA, and combined EVA+IVA exposures ? Acute Radiation Response Models will be modified to account for updates to RBE values as determined by research described in Gaps 1 and 2. SPE probabilistic modeling will be used as input to response models for overall risk assessment. Collaboration with other NASA Programs will facilitate probabilistic SPE modeling efforts in terms of probability of occurrence and time scale of accumulated dose. These models will be refined as necessary with updates to tools that can predict changes to the local space radiation environment including the probability of crew exposure levels and time to designated radiation shelter.
Application of probabilistic risk assessments models to EVA + IVA scenarios for skin, blood forming organs (BFO) and other organs (Acute Radiation Response Models model updates).
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Contents 1.AE9/AP9/SPM
2.OLTARIS
3.Astronaut EVA Exposure Estimates from CAD Model Spacesuit Geometry
4.Comparison of space radiation doses inside the Matroshka-torso phantom installed outside the ISS with the doses in a cosmonaut body in Orlan-M space suit during EVA
5.Construction of boundary-surface-based Chinese female astronaut computational phantom and proton dose estimation
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AE9/AP9/SPM AE9/AP9 is the next generation specification of the natural trapped radiation environment near Earth.
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D ID YOU KNOW ? D OSE REDUCTION EFFECTS FOR SPACE RADIATION BY IN STALLATION OF WATER SHIELDING MATERIAL
The International Space Station (ISS) crew is constantly exposed to space radiation consisting of different kind of charged particles with various energies and nuclear charges. The radiation dose comes mainly from protons and helium ions which are mostly present in space radiation. The contribution of heavy components (Z > 2 ions) makes increase of dose equivalent due to the high LET (linear energy transfer) with high quality factor related to the relative biological effectiveness (ICRP,1991). Moreover, primary high energetic charged particles produce not only secondary charged particles but also fast neutrons due to nuclear interaction with materials. The biological effects by fast neutrons are also considerable component in terms of the space radiation dose equivalent. The typical daily dose in the ISS is ranging from about 0.5 to 1 mSv depending on the solar activity and the altitude and attitude of the ISS. The effective dose limits of 10 yr career for astronauts are recommended to be 400 mSv (female) and 700 mSv (male) for 25 yrs old(NCRP No. 142, 2002). The radiation risk of astronauts in the ISS is controlled under such recommended limitations with actual dose measurement.
The material of the protective curtain consists of the hygienic wipes and towels which have been already installed in the Russian Service Module as shown in Fig. 1. The hygienic tools were stored into the protective curtain at 4 layers, which is corresponding to the additional water shielding thickness of 6.3 g/cm2 . The total mass of the protective curtain is 67 kg, it was installed along the outer wall of the starboard crew cabin in the Russian Service Module.
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The use of passive dosimeter packages to verify the dose reduction effect for space radiation by installation of protective curtain. The 6 packages were located on the protective curtain surface and the other 6 packages were located on the crew cabin wall behind or aside the protective curtain. The mean absorbed dose and dose equivalent rates are 327 µ Gy/day and 821 µSv/day for the unprotected packages and 224 µGy/day and 575 µSv/day for the protected packages, respectively. The mean dose reduction rate obtained from the dose change among protected and unprotected package pair was 37 ± 7% in dose equivalent, which was consistent with the calculated results in the spherical water phantom by PHITS.
Original Published at ScienceDirect
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OLTARIS OLTARIS provides the ability to add a human phantom into an uploaded space vehicle shielding distribution, to enable the calculation of whole body effective dose. The CAM (Computerized Anatomical Male) and CAF (Computerized Anatomical Female) are established reference body models that are based upon geometric models of the body’s tissues.The phantom tissue distributions for either the CAM or CAF have been pre-calculated and are added to the space vehicle thickness distributions after they are uploaded to OLTARIS.
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Astronaut EVA Exposure Estimates from CAD Model Spacesuit Geometry
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This model consisted of 28 components representing the different elements of the suit, visors, and PLSS. Because of the complexity of the model, the finite element model has over 30,000 facets. This FEM was then used in the ray-tracing procedure to determine the directional shielding at a given target point. In Fig. 4 it is shown the FEM of the Shuttle EVA Spacesuit. For the various space suit components, values for the density are obtained as averages. But for the LCVG, an average areal density taken only from the values for the fabric is inaccurate because the water-filled tubes cover approximately 40% of the surface area. This results in an in homogeneous structure that can’t be well represented by only the fabric mean areal density. In a model of the actual fabric/tube transmission properties, the water-filled tube geometry must be dealt with specifically by the transport through actual material layers as opposed to assuming homogeneity and by the performance of particle transport experiments to provide data for the development of models of inhomogeneities within the fabric. These tasks were performed at the LBNL 88” cyclotron with a 35MeV proton beam, and the fabric transmission properties are represented as an analytical model that has good agreement with low-energy proton transmission testing. The fabric is best fitted as a normal distribution of material of mean thickness of 0.161 ± 0.03 g/cm2 of material, with its mean areal density without cooling tubes being 0.185 g/cm2 . The chemical composition for this, as for all other space suit components, needed to be known, but in the transport codes used in the analysis, it needed to be limited to only six atomic elements. Table 3 lists each component along with its modeled composition andmass properties. When the CAD model mass is compared to the actualmass of the suit, the PLSS and the EVVA mass estimates are close. For the space suit assembly (SSA) itself, the values are much lower. This is believed to be because the disconnects for the gloves, the HUT, and the arm assembly have not been built into the model, a result of their small solid angles. The dose at a location within the astronaut’s body is evaluated by considering the surrounding shielding by the ISOPTWPO Today Page 14 International Space Agency(ISA)
Gap’s in NASA Human Reserach Roadmap space suit materials and body tissues. For a given point in the target, the space suit material distribution was evaluated along 968 ray directions. This distributionwas chosen tomatch the ray distribution used in the CAM data, each one with a fixed solid angle (∆Ω = 4π/ 968).
To better understand these distributions and their effects, two methods have been used to visualize the results of the ray tracing. The first is the visualization of the rays as they intersect the material throughout the suit. In the example in Fig. 10, the projected rays through the space suit materials in and around a point in the sternum is shown, with the shielding role of the EMU lights and camera, the backpack, and the DCM clearly evident. Another visualization technique is the projection on a sphere by a color scale of the relative shielding within the suit around the dose point, as shown in Fig. 11. If the sphere is fully rotated, the shielding in the total solid angle from every ray direction is examined. To obtain results representative of the whole human body without actually performing the analysis for the entire set of the 147 CAM data points, the analysis was limited to nine points, namely, three skin points (shin, thigh, and chest), two Blood- Forming Organ (BFO) points (pelvis and sternum), and four organ points (thyroid, colon, testes, and lens). These nine points were then run through the electron transport code, ELTRN, for solar minimum and maximum conditions for one, two, and three (storm scenario, which is discussed previously) sigma. These points were also run through the proton code, HZETRN, for solar minimum and maximum conditions. Two space suit layouts are considered in the computation with the LCVG fabric viewed as a monolayer average density fabric and the tube structure of the LCVG resulting in shielding nonuniformities. The results are shown in Table 4 (a, b) and Table 5 (a and b),with the explanation of the abbreviations given in Table 6. By comparing Table 4b to Table 5b,we see that the self-shielding of the body contributes significantly to protecting the BFO and other organs fromthe trapped electron radiation, whereas the suit itself does not providemuch protection. The trapped proton radiation is much less intense at the skin point locations compared to the electron radiation, but it does penetrate through the body and constitutes most of the dose received by internal organs. All results are to be comparedwith the dose limits recently proposed by NCRP, shown in Table 7.
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Comparison of space radiation doses inside the Matroshka-torso phantom installed outside the ISS with the dosesina cosmonaut body in Orlan-M space suit during EVA Russian crew members use Orlan-M spacesuit in EVA.Recently some attempts have been made to calculate dose
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Gap’s in NASA Human Reserach Roadmap distribution in cosmonaut’s body on the International Space Station (ISS), the calculation method is based on the Orlan-M shielding data used together with model descriptions of the space radiation sources. Many factors should be taken into account that makes influence on the dose distribution in the cosmonaut’s body, such as additional shielding of the space station constructions, the body attitude to the space station surface (”standing”, ”lying”), the body orientation to the East-West direction, and others. Such factors make the calculations very laborious; the data obtained are difficult to apply to real EVA, as there is an additional uncertainty in the radiation environment models. Thus, the space experiments aimed on the study of the dose distribution in human body during EVA are very important. Such study was realized in 2004-2005 years when in the framework of the Russian space experiment Matroshka-R, the dose distribution in an upper torso phantom was measured. The torso phantom was placed in the special spacesuit-simulating container and installed on the outer surface of the ISS Service Module. Because of the existing technical restrictions on dimensions of payload to be delivered to ISS and then installed on the outer surface in EVA, the cut-down anthropomorphic phantom of Rando type is used in Matroshka experiment to evaluate doses in critical organ sites. The Torso-phantom is only an upper part of the body without arms and legs placed in the container. It should be noted that obviously the container and cut-down Rando phantom used in Matroshka experiment are different than the Orlan-M spacesuit and the cosmonaut’s body described by the full anthropomorphic phantom in the Russian standard. The mentioned difference implies an additional analysis of the experimental data obtained in Matroshka experiment to make the data obtained applicable to EVA conditions in Orlan-M space-suit. The Matroshka-Torso phantom in the container was installed on the universal working platform perpendicular the space station surface; main technical parameters of the Matroshka hardware are presented in Table 1. Table 2 gives dates of main events of the Matroshka experiment; Table 3 gives durations of main phases of the experiment.
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No powerful solar energetic particle events that could influence the ISS crew dose were registered during the Matroshka-Torso experiment in 2004-2005; detector exposure duration inside the ISS was less than 15% of that outside the station. More than 1000 passive thermolumi-nescent detectors (TLD) provided by international partners were used in the experiment, IBMP detectors included, that allowed to make a detailed study of the dose distribution. A control detector package was located in the Service Module to obtain the estimation of the Matroshka-Torso detector doses while inside the space station before and after the exposure on the outer surface. Comparison between Matroshka-Torso experimental results and calculated doses is given in Fig. 1, coordinates of the detector locations in representative points of critical organs in the Torso-phantom are presented in Table 5. For practical purposes, it is important to compare the exposure conditions of the Matroshka-Torso inside the container with that of cosmonaut in Orlan-M spacesuit during EVA. The mass of the container is only 4.07 kg that is essentially smaller than that of the equipped Orlan-M spacesuit (110 kg). Because of the construction properties, the spacesuit shielding has an asymmetry in the mass distribution in the forward-back direction, the shielding from the backward direction is bigger than that from the forward one.
In Table 6, the coordinates of selected representative points in the phantom are presented that are used for the Matroshka-Torso and Orlan-M spacesuit comparison.
In Fig. 2, the shielding functions are presented for representative points of the Matroshka-Torso phantom inside the container and for corresponding representative points of the anthropomorphic phantom in Orlan-M spacesuit. As it can be seen in Fig. 2, in most cases the shielding of representative points in Orlan-M spacesuit is higher than that for the Matroshka-Torso inside the container. However, in case of ”Eye lens 1”, ”Eye lens 2” and ”Skin 2” the relation
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Gap’s in NASA Human Reserach Roadmap is different, namely, the Matroshka-Torso shielding is practically the same as in Orlan-M spacesuit for ”Eye lens 1” and even higher than corresponding Orlan-M shielding for ”Eye lens 2” and ”Skin 2”.
For typical ISS orbit (altitude 350 km and 51.61 inclination) in solar minimum and solar maximum, the doses in corresponding representative points of the Matroshka-Torso phantom inside the container and the anthropomorphic phantom in Orlan-M spacesuit were calculated. The calculated dose equivalent ratios H(Orlan-M)/H(Matroshka-Torso) are presented in Table 7.
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As obtained in the calculations, the ratios H(Orlan-M)/ H(Matroshka-Torso) vary from 0.1 to 1.8 as dependent on the selected critical organ and solar cycle phase. Obviously, in some cases the Matroshka-Torso doses are higher than that in the Orlan-M spacesuit and over-estimate EVA doses; but in other practically important cases, the Matroshka-Torso doses underestimate the radiation loads on human body in Orlan-M spacesuit. As expected from comparison of the shielding functions, in case of ”Eye lens” when EVA with the sunlight protector of the helmet, the doses in Matroshka-Torso experiment are close to that in Orlan-M spacesuit both in solar minimum and in maximum. For relatively heavy shielded representative points of the critical organs (BFO chest, BFO back and Testis), the doses measured in Matroshka-Torso are from 20% to 30% higher than doses in real EVA in Orlan-M spacesuit, thus Matroshka-Torso doses can be considered as conservative estimation of the EVA doses. In case of ”Skin 1” point, the Matroshka-Torso dose over-estimation is ≈ 3 times in solar minimum and ≈ 10 times in solar maximum that is caused by strong difference in corresponding shielding functions (see also Fig. 1). For less shielded critical organs ”Skin 2” and ”Eye lens 2”, the dose relationship is inverse, namely, the dose equivalent in real EVA in Orlan-M spacesuit is expected to be from ≈ 30% to ≈ 80% higher than that measured in MatroshkaTorso. Thus, ”Skin 2” and ”Eye lens 2” organs are most exposed to space radiation in real EVA, however shielding conditions of these organs are not simulated in Matroshka-Torso experiment outside ISS. The above-calculated dose ratios should be taken into account when transferring the data of Matroshka-Torso experiment to the EVA radiation conditions in Orlan-M spacesuit. To estimate the human body doses in Orlan-M spacesuit in EVA conditions that are close to those in Matroshka-Torso experiment, the experimental results should be multiplied by the corresponding ratios pre-sented in Table 7. In case of EVA conditions different from those in Matroshka-Torso experiment, the human body dose estimations can be obtained by using the calculated shielding functions for selected representative points together with depthdose curves corresponding to real EVA space radiation exposure conditions. The shielding properties of Orlan-M spacesuit used in real EVA are essentially different from that of the Matroshka-Torso container. The shielding probability functions for human critical organs in Matroshka-Torso phantom inside the container are calculated based on geometry model and technical description of the Matroshka experimental facility. Similar shielding functions are calculated for the Orlan-M spacesuit using its technical description and the results of the space-suit shielding on-ground study by gamma-transmission method. The calculated ratios of dose equivalents in critical organs of the Orlan-M spacesuit to that in Matroshka-Torso H(Orlan-M)/H(Matroshka-Torso) vary from 0.1 to 1.8 as dependent on the selected critical organ and solar cycle phase.
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D ID YOU KNOW ? M EASUREMENT OF THE D EPTH D ISTRIBUTION OF AVER AGE LET AND A BSORBED D OSE I NSIDE A WATER -F ILLED P HANTOM ON B OARD S PACE S TATION MIR At the orbit of the Space Station MIR ≈ 380 km the main part of the primary radiation field is due to the GCR and the trapped protons of the South Atlantic Anomaly. Measurements on Space Station MIR showed, that the ratio of dose equivalent from GCR to protons is about 3/2:1. Interaction of this radiation field with the hull of the spacecraft results in a complex secondary radiation field consisting of charged particles, neutrons, gamma and X-rays, brems-strahlung as well as π and m-mesons. A considerable component of that field are particles with a high linear energy transfer resulting in very high biological effectiveness.
For the estimation of organ doses and thus the radiation risk measurements in phantoms are essential. The aim of the project Phantom 1-3 was to measure the depth distribution of absorbed dose and ’averaged’ LET in dependence on the position of the phantom inside the Space Station MIR and on the positions of the dosemeters inside the phantom (perpendicular and parallel to the hull of the spacecraft). By evaluating of the ’averaged’ LET it is further possible to obtain information about the depth dependence of the dose equivalent and so the biologically relevant dose. A water filled phantom with a diameter of 35 cm was developed by the Institute of Biomedical Problems in Moscow. This phantom consists of 4 channels which are positioned in right angle in one plane inside the phantom. In these channels dosemeters of the types TLD 600 (6 Li enriched) and TLD 700 (7 Li enriched) were exposed in different depths. Due to their small dimensions TLD’s are very suitable for measurements inside phantoms. The dosemeter were evaluated using the HTR method. Figure 2 and Figure 3 show the summary of the depth distribution of absorbed dose for projects Phantom 1-3. In Figure 2 a stronger decrease in absorbed dose for Phantom 1 and 2 is due to the nearer position of the dosemeters in channel number 2 to the hull of the spacecraft.
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During the duration of Phantom phase 1 and 2 absorbed dose rates are almost independent of the position of the phantom. The dose rate for Phantom 3 is lower in channels number 1 and 3. This can be explained by the different shielding condition of phase 3 (Modul Kwant 2) and the changed position of the dosemeters within the phantom (parallel to the hull of the spacecraft). The difference in TLD - 600 and TLD 700 could be explained by the thermal neutrons which are detected by TLD - 600 over the 6 Li(n,α)3 H reaction. The ’averaged’ LET evaluated with the HTR method can be seen in Figure 4 and Figure 5. The evaluation is based on the LET calibrations with ions of different LET. Whereas the ’averaged’ LET for TLD - 700 shows no significant change by increasing depth for all 3 Phantom exposures, the ’averaged’ LET for TLD - 600 is increasing with increasing depth.
This is due to the increasing part of thermalized neutrons inside the phantom. Although the absorbed dose decreases, the dose equivalent rate remains almost constant over the whole depth of the phantom. Phantom 1: TLD - 600: 776 ± 29 µSv/d and TLD - 700: 574 ± 60 µSv/d; Phantom 2: TLD - 600: 770 ± 28 µSv/d and TLD - 700: 535 ± 40 µSv/d; Phantom 3: TLD - 600: 730 ± 40 µSv/d and TLD - 700: 436 ± 35 µSv/d.
The difference in Phantom 1 / 2 to Phantom 3 is due to the different shielding conditions and the changed position of the dosemeters inside the phantom. References: NCBI
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Gap’s in NASA Human Reserach Roadmap Construction of boundary-surface-based Chinese female astronaut computational phantom and proton dose estimation In the 1970s, the National Aeronautics and Space Administration (NASA) of the USA developed a computational anatomical male (CAM) phantom and a computational anatomical female (CAF) phantom for risk assessment of space radiation. The utility of the anatomical models for estimating exposure to specific body organs has been demonstrated by the creation of mathematical phantoms, a type of computational phantom with a history of more than 40 years, in which equations are utilized to define the body shape and internal organs. Besides the mathematical phantom, a voxel-based phantom is also employed, with a number of person-specific phantoms. Also used in space radiation dosimetry is the Golem phantom from the Gesellschaft fur Strahlenforschung (GSF) voxel-based phantom family, which was derived from whole-body computed tomography (CT) examination of a male leukaemia patient. The CAM and CAF phantoms are modelled using constructive solid geometry (CSG) techniques, which facilitate rapid dose calculation, but these phantoms are limited in their ability to represent anatomical details. The Golem phantom is a typical voxel-based phantom, being based on voxel matrices segmented from tomographic images. The advantage of this type of phantom is its improved anatomical fidelity, while having the disadvantage of discontinuities around organ contour and contact regions. In addition, scaling of the phantom can only be performed by adjusting the voxel dimensions. With the development of computer graphics, Non-Uniform Rational B-Spline (NURBS) has been increasingly employed for boundary representation in phantoms because of its benefits in terms of anatomic realism and spatial deformation, and the fact that it takes advantage of the most desirable features of both the mathematical phantom and the voxel-based phantom. Authors developed a computational anatomical phantom by NURBS modelling of the cryosectional colour photographic images of a 19-year-old adult female cadaver. The phantom was further tailored according to the physical characteristics of Chinese female astronauts and the International Commission on Radiological Protection (ICRP) reference adult female. Using the Monte Carlo code MCNPX, proton radiation transport was simulated with a wide energy range, and organ-absorbed doses and effective doses were calculated. Results were then compared with the MIRD female phantom, the ICRP female phantom, the VCH male phantom and the sex-averaged doses. Fast approximate calculation of daily skin dose was achieved based on the skin organ dose and the on-orbit proton spectrum from the Shenzhou spacecraft. Three-dimensional structure of the VCH-FA NURBS phantom A 3D view of the Visible Chinese Human adult Female Astronaut (VCH-F) NURBS phantom is shown in Fig. 2. The skin and muscle are set to translucent to enable visualization of the internal organs and skeleton. More than 30 organs and tissues are defined. As a representative system containing small structures, the urogenital system was carefully identified and modified. A 3D view of the urogenital organs is shown in Fig. 3a. The models of the large and small intestine in Fig. 3b show a high degree of local detail. Every effort has been made to ensure that the anatomical characteristics of the final VCH-FA phantom provide a scientific and valid basis for the intended application.
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Comparison of VCH-FA phantom and VCH male phantom The most significant difference between male and female phantoms is the reproductive system (ovaries, oviduct, uterus, vagina, breast etc. in females), which is of critical importance in terms of human physiological and physical characteristics. In the VCH-FA phantom, the reproductive system was identified in great detail, especially the oviducts, ureters, urethra and vagina. These small organs are not included in most other phantoms or reference data. Comparison of the mass of the main tissues and organs between the VCH-FA phantom and the VCH male phantom revealed similar masses for most organs, with ratios of 0.78-1.38 for the adrenals, brain, oesophagus, eyeballs, gallISOPTWPO Today Page 24 International Space Agency(ISA)
Gap’s in NASA Human Reserach Roadmap bladder, heart, intestines, kidneys, liver, red bone marrow (RBM), salivary glands, skin, thymus, thyroid and urinary bladder (average relative deviation, 1.38%). Greater discrepancies in mass were found in four organs, with relative deviation of 135% for the pancreas, 46% for the skeleton, 40% for the stomach and 39% for the spleen. Difference in organ mass between the genders is attributable to body sizes and physiological features. In addition, lung mass of the VCH-FA phantom is 52% of that of the VCH male phantom, because in the latter, blood is included in the total lung mass. The total mass of the reproductive organs is 602.08 g (breasts, ovaries, oviducts, uterus and vagina) in the VCH-FA phantom, and 40.60 g (epididymes, prostate and testes) in the VCH male phantom. The reproductive organs play an important role in space radiation studies and their tissue weighting factors are of great importance in determining effective dose. Hence, the efforts in the present study to produce accurate and reliable representation of urogenital organs represent an important contribution for the evaluation of radiation risks to female astronauts. Comparison of VCH-FA phantom with other female phantoms Table 3 lists published organ and tissue masses for several female phantoms (including the adrenals, brain, breasts, colon, oesophagus, eyeballs, gallbladder, heart, intestines, kidneys, liver, lungs, ovaries, pancreas, salivary glands, spleen, thymus, thyroid, ureters, urinary bladder, and uterus) as well as a comparison of differences in organ mass between the VCH-FA phantom and other adult female phantoms.
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Because mass adjustment was performed (as described above), VCH-FA organ masses show excellent agreement with the values from the ICRP reference female, within 1% relative deviation, with an average relative deviation of - 0.26%. The reason for the discrepancy is that blood is not included in the VCH-FA phantom. The total body weight of the VCH-FA phantom is in line with the value stated by the Chinese National Standard of Occupational Health regarding reference individuals for use in radiation protection (54 kg). The relative deviations in organ mass between VCH-FA and the IAEA reference Asian female are greater, with 14 organs within 10%, 11 organs between 10% and 30%, and 4 organs greater than 30%, although the average organ mass deviation is 8.48%. The total body weight of the IAEA reference Asian female is 51 kg, which is 5.56% less than VCH-FA. Comparing VCH-FA with the MIRD phantom, the mean mass deviation is 7.36%, with only three exceptions beyond 30%. The values for thyroid, breast and pancreas are 36.00%, 37.44% and 81.38%, respectively. The difference in the mass of the pancreas represents a significant difference, which is mainly derived from the definition method ( particularly shape restrictions) of the MIRD phantom. Organ-absorbed dose and comparison Proton transport was simulated in the VCH-FA phantom, the MIRD female phantom, the ICRP reference female phantom and the VCH male phantom under strictly the same conditions. The organ doses were calculated under proton energies ranging from 5 MeV to 10 GeV. Figure 4 compares the evaluated organ doses for the skin, lungs, colon, stomach, liver and the RBM of the phantoms. The sharp, narrow peaks on the absorbed dose curves reflect proton absorption in tissue from energy loss as the particles travel through biological tissues. The peak energy varies according to the distance to the target organs from the outline surface. As the energy increases for proton energy lower than 1000 MeV, the organ dose curve first rises before falling, presenting a local maximum related to the Bragg peak of protons characterized by the fact that their tracks are almost completely absorbed within the organs. When proton energy is relatively low, most protons are stopped within a short depth of penetration and deposit most of their energy in the skin, which can be seen in the distinctive absorbed dose curves for the skin. When proton energy is above 50 MeV, the protons and secondary particles are able to travel farther to the internal organs. Protons slow down relatively quickly when they pass through biological tissues, with most of their energy deposited at the end of their path as Bragg peaks. Hence, the internal organs yield higher doses during irradiation to reach maximum values of around 100-200 MeV. Discrepancies in absorbed dose for the same organs among the four phantoms at 100, 200 and 1000 MeV ranged from -0.33% to -16.05% for skin, -0.17% to 28.33% for lungs, 0.45% to 170.87% for colon, 1.99% to -29.15% for stomach, 0.49% to 16.97% for liver and -1.34% to 82.37% for RBM. Among these, RBM was not included in the MIRD female phantom because of the difficulty in defining the numerous discrete parts via mathematical equations. The comparison of radiation quantities among the VCH-FA phantom, the VCH male phantom, the MIRD female phantom and the ICRP female phantom suggests that absorbed proton doses for organs are related to many factors, including definition type, organ mass and anatomical structure (e.g. position, distribution and geometry).In VCH-FA and MIRD, dose deviation was greater than 10%, even above 100 MeV, for skin, lungs and stomach. The mean dose deviations of these three organs were -16.92%,-11.76% and -24.37%, respectively. As mentioned above, the mass deviations were -0.03%, -27.30% and 18.46%, correspondingly. The stomach has the smallest organ mass in the MIRD female but receives the highest absorbed dose per fluence because it is close to the body surface. Furthermore, although organ mass differences are greater between VCH-FA and the VCH male than between VCH-FA and MIRD, dose discrepancies are more obvious in the MIRD phantom, which indicates that definition type is of great importance for dose calculation. The results also imply that absorbed dose is sensitive to the distance from the outline surface to the concerned organ or system. In radiation dosimetry practice, it is difficult to represent the correct depth of all internal organs in the simplified trunk of the MIRD phantom, and this may result in overestimation of absorbed dose for some internal organs, especially for relatively low energies at critical values of particle penetration. Regarding RBM, the masses of three phantoms were similar, with discrepancies of around 7.00%, but dose deviation comparing the VCH-FA phantom with the ICRP phantom exceeded 40.00% at energy from 50 MeV to 100 MeV, and was within 5.00% from 200 MeV to 10 000 MeV. The dose discrepancies arise mainly from the differences in RBM distribution, which are related to the segmentation method.
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When the proton energy is higher than 1000 MeV, the dose curves rise continuously. Dose deviation is less prominent at higher energy than at lower energy because statistical uncertainties are reduced when particles penetrate through body tissue. The radio-sensitivity of the reproductive system makes it particularly important to obtain accurate and reliable dose for sex-specific organs. Comparing absorbed dose in the reproductive system among the three female phantoms, results show remarkable agreement within the limits of statistical uncertainty. As illustrated in Fig. 5, mean organ dose ratios for the VCH-FA phantom compared with the MIRD and ICRP phantoms at energy levels above 150 MeV were 99.02% and 99.70% for the ovaries, 98.00% and 102.57% for the uterus, and 98.65% and 103.90% for the breast, respectively. The mass ratios were 99.45% and 102.15% for the ovaries, 99.38% and 100.58% for the uterus, and 99.20% and 137.44% for the breast, respectively. From 50 MeV to 100 MeV,mean dose ratios were 59.75% and 72.75% for the breast. This result indicates that the dose discrepancy is closely related to the particle energy. In the high-energy range, dose ratios tend towards constant values. These results also verify that as well as mass, other important factors influencing organ dose are anatomic position, organ shape and distance to
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In addition, Fig. 6 shows that at energies from 20 to 50 MeV, absorbed dose for breast is much lower in the VCH-FA compared with the other phantoms, while doses for the ovaries and uterus are well correlated; at higher energies, the difference in absorbed dose for breast between the VCH-FA and other phantoms decreases. The results may be attributed to the thicker skin in that region of the VCH-FA phantom. At low energies, the penetration depth of protons is limited . Most of the low-energy protons are absorbed in the skin, with few deposited in the breast. Although our findings demonstrate that the skin will have little influence on absorbed dose in the inner organs, for breast tissue, the Bragg peak shifts towards higher energies at about 20 MeV. At lower energies, the doses to shielding layers increase with rising energy when the Bragg peak is developed in them. The effect of particle penetration will decrease if the stopping power of the shielding layers improves with an increase in layer number or an increase in areal density. Particles able to penetrate the shielding layers must then be of even higher energies, and thus the Bragg peak may shift towards a higher energy range within the body of the astronaut. In the simulations, statistical uncertainty in most organs was less than 2.00%, which is more precise than in the results commonly obtained by dosimeters in physical experiments. However, small organs such as the oviducts, urethra, adrenals, thyroid and thymus present relatively high statistical uncertainties of between 1.00% and 10.00%. Statistical uncertainty is estimated as less than 11.00% in deeply located internal organs. Effective dose and comparison Table 4 summarizes the results of effective dose per unit fluence under ISO irradiation of proton-initiated incident radiation with all transported particles for the VCH-FA phantom, VCH male phantom, MIRD female phantom, and ICRP female phantom. The sex-averaged dose was calculated by the arithmetically weighted value of VCH-FA and VCH male data, and complied with that recommended by ICRP103. The effective dose curves for VCH-FA, VCH male, sexaveraged, MIRD female and ICRP female phantoms all present the same trend, as shown in Fig. 7. For energies below 150 MeV, the effective dose curves rise rapidly with increasing energy levels, and reach peaks at proton energies of approximately 150 MeV. The peak is caused by the Bragg peak of protons at that energy. There is a large variation in values in this range, and the slopes of the curves are steep. The minimum and maximum effective doses per fluence are 0.45 and 2112 pSv cm2 , respectively. After the local maximum of effective dose, the value first decreases in the range of 150-1000 MeV, before rising once more. The increase in effective dose at the end of the curves is caused mainly by the effect of intensive nuclear inter-
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Gap’s in NASA Human Reserach Roadmap actions. The effective doses are well correlated at high energies, where the penetrating power of the protons is much stronger and anatomical structure has less influence.
There were no large dose discrepancies among the sexaveraged, VCH-FA and VCH male phantoms, but objective differences do exist. The minimum and maximum absolute differences of effective dose per fluence are 0.10 and 183 pSv cm2 , respectively. The results of the present study indicate that a degree of uncertainty would exist if radiation protection quantities from only one gender were considered as standards. Consequently, dosimetry of the VCH-FA female phantom and calculation of the sex-averaged dose are necessary for estimation of space radiation dose.
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Gap’s in NASA Human Reserach Roadmap We multiplied the organ doses by the tissue weighting factors and radiation weighting factors provided in ICRP Publication 103. Tissue weighting factors for breast and skin are 0.12 and 0.01, respectively. As mentioned above, locally thick skin results in the right-shift phenomenon, and thus the absorbed doses for breast brought about a 64172pSv cm2 reduction in the effective dose at 20-50 MeV for VCH-FA, compared with that for the ICRP female phantom. The calculated effective doses are significantly lower for VCH-FA than for the ICRP female at these low energies. The dose ratios between VCH-FA and the ICRP female are only 45.45% at 20 MeV, 31.09% at 30 MeV and 59.26% at 50 MeV. The corresponding values are 96.27-110.10% for energy levels higher than 75 MeV. These comparisons suggest that for low-energy proton transportation, the local skin thickness influences female effective dose, especially in the thoracic cavity region. The results also indicate the distinctive features of the VCH-FA phantom compared with other phantoms, and prove the value of the VCH-FA phantom for dosimetry of Chinese female astronauts.
Dose assessment for space radiation
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Gap’s in NASA Human Reserach Roadmap Figure 8 shows the proton spectrum used in our calculations, which was obtained from trapped proton model PSB97 during missions of the Shenzhou spacecraft series in LEO, with eccentricity of 0.0002767, inclination of 42.4211◌ , perigee height of 332 km and apogee height of 336 km.
The actual measurement values ranged from 0.20-0.50 mGy/day for Shenzhou spacecraft series operations, with an average value of 0.29 mGy and error within 5%. These values are in line with mission measurement data from the American space shuttle and do not exceed the Chinese National Standard of Radiation Protection requirements for spacecraft crew modules (ID: GJB 4018-2000). The calculated result of skin-absorbed dose under shielding for this mission is 0.27 mGy per day, which differs from the measurement value by 6.90%. The calculated whole-body daily dose is 0.18 mGy, which reflects a certain loss of energy in the process of penetrating the material, with fewer radiation particles able to pass through and reach the human body, thus decreasing the organ doses after shielding.
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Gap’s in NASA Human Reserach Roadmap As shown in Fig. 9, organ dose ratios range from 0.758-0.991, with an average value of 0.861. These values indicate that the shielding effect reduces organ doses by about 14%. A special case is the skin, the outermost layer of the phantom, which has a dose ratio of 0.478. From the curve of absorbed dose per proton fluence for skin without shielding, the Bragg peak characteristic at about 20 MeV has been observed, as discussed above. For a shielding thickness of 1.35 g/cm2, particles below 30 MeV are restrained, while fluences are high in that range; this explains the 52.20% decrease in skin dose.
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D ID YOU KNOW ? I NTEGRATIVE R ISK M ODELS T OOLKIT ARRBOD The space radiation environment, particularly solar particle events (SPEs), poses the risk of acute radiation sickness (ARS) to humans; and organ doses from SPE exposure may reach critical levels during EVAs or within lightly shielded spacecraft. NASA has developed an organ dose projection model using the BRYNTRN with SUMDOSE computer codes, and a probabilistic model of Acute Radiation Risk (ARR). The risk projection models of organ doses and ARR take the output from BRYNTRN as an input to their calculations. With a graphical user interface (GUI) to handle input and output for BRYNTRN, the response models can be connected easily and correctly to BRYNTRN in a user-friendly way. A GUI for the Acute Radiation Risk and BRYNTRN Organ Dose (ARRBOD) v1.0 considered the prodromal syndrome and included several historical SPE spectra. ARRBOD v2.0 assesses the resultant early radiation risks from the blood forming organs (BFO) dose by using four biomathematical ARS models of lymphocytes depression, granulocytes modulation, fatigue and weakness syndrome, and upper gastrointestinal distress. The ARRBOD GUI is intended for mission planners, radiation shield designers, space operations in the mission operations directorate (MOD), and space biophysics researchers. Reference:http://spaceradiation.usra.edu/downloads/arrbod/ GERMCode The GCR Event-based Risk Model (GERM) code is a stochastic model of space radiation transport being developed for new risk assessment approaches. The GERM code was built on the QMSFRG (quantum multiple scattering fragmentation) model and atomic interaction models used in HZETRN (high-charge and high-energy transport). Descriptions of particle track include the radial dose distribution and frequency of energy deposition in DNA volumes. Dose response models for cell survival and mutation, and Harderian gland tumors in mice described for mono-energetic or mixed particle fields behind shielding. The GERMcode is in excellent agreement with the NASA Space Radiation Laboratory (NSRL) and other laboratory physics measurements of fragmentation cross sections, particle fluence distributions, and the Bragg depth-dose curve. The GERMcode provides scientists participating in NSRL experiments: data interpretation of their experiments; the ability to model the beam line, shielding of samples and sample holders; and estimates of basic physical and biological outputs of experiments. The GERMcode will be the main tool to develop new time dependentstochastic descriptions of biological responses of interest for space radiation protection and Hadron therapy. Reference:http://spaceradiation.usra.edu/downloads/germcode/ NASARTI The NASA Radiation Track Image v3.0 (NasaRTI v3.0) has a compendium of codes and functions to model the effects of the high-charge high-energy (HZE) ion components of the galactic cosmic rays, which present unique challenges to biological systems in comparison to terrestrial forms of radiations. The GUI operates a deoxyribonucleic acid (DNA) breakage model to visualize and analyze the impact of chromatin domains and DNA loops on clustering of DNA damage from X-rays, protons, and HZE ions. The model of DNA breakage includes a stochastic process of DNA double-strand break (DSB) formation and is based on the averaged radiation track profile and a polymer model of DNA packed in the cell nucleus. Additionally, the NasaRTI provides a function to analyze patterns of DNA damage foci, especially from high-LET particles, which have characteristic streak-like patterns. To improve comparisons with the manual count of foci, the package includes a segmentation algorithm, for counting objects (including simple and co-localized DNA damage foci) in experimental images. In the NasaRTI v3.0, we include a radiated tissue model to provide an analysis tool of radiobiological data on tissue level. Reference:http://spaceradiation.usra.edu/downloads/nasarti/
Gap’s in NASA Human Reserach Roadmap RITRACKS RITRACKS is a Monte-Carlo code for the simulation of heavy ion and d-ray tracks in biomolecules using accurate ionization and excitation cross sections for liquid water. RITRACKS provides detailed information on energy deposition and production of radiolytic oxidative species, that damage cellular components, in targets and voxels of different sizes at the micro or nano scale. RITRACKS provides a useful evaluation tool over the charge and energy range of interest for space radiation protection and Hadron therapy studies. It also provides the visualization capability of the microscopic 3-D tracks. RITRACKS will provide stochastic track descriptions of the whole genome by improving the radiation chemistry algorithms of other species and including various biological targets. Reference:http://spaceradiation.usra.edu/downloads/ritracks/ HemoDose To guide medical personnel in making clinical decisions for effective medical management and treatment of exposed individuals in a radiology/nuclear disaster event, biological markers that reflect radiation induced changes may be employed to assess the extent of radiation injury. Among these markers, the most widely used are peripheral blood cell counts. The HemoDose tools are built upon solid physiological and pathophysiological understanding of mammalian hematopoietic systems, and rigorous coarse-grained bio-mathematical modeling and validation. Using single or serial counts of granulocyte, lymphocyte, leukocyte, or platelet after exposure, these tools can estimate absorbed doses of adult victims very rapidly and accurately. Patient data in historical accidents are utilized as examples to demonstrate the capabilities of these tools as a rapid point-of-care diagnostic or centralized high-throughput assay system in a large scale radiological disaster scenario. Unlike previous dose prediction algorithms, the HemoDose tools establish robust correlations between the absorbed doses and victim’s various types of blood cell counts not only in the early time window (1 or 2 days), but also in very late phase (up to 4 weeks) after exposure. Reference:http://spaceradiation.usra.edu/downloads/hemodose/ Online Tools and Models ARRBOD 2.0 Web Server Solar Particle Events (SPEs) occur quite often over the approximately 11-year solar cycle, but are highly episodic and almost unpredictable. They represent a major threat to crews of space exploration missions. During such events, the flux of protons with energy greater than 10 MeV may increase over background by 4 to 5 orders of magnitude for a period of several hours to a few days. The hazards of exposure to these large doses have to be evaluated in the context of the high competing risks of vehicle or life support system failures. In addition to the risk of cancer and other late effects such as the neuronal and heart disease risks and cataracts, the appraisal of Acute Radiation Sickness (ARS) assumes prime importance because it can impair the performance capabilities of crew members and thereby threaten mission success. In this ARRBOD web server, the Baryon transport (BRYNTRN) code is used to transport primary SPE protons and their nuclear reaction products through various media for the estimation of organ doses. The radiation shielding by body tissue at specific organ sites was accounted for by using ray tracing in the human phantom models of the Computerized Anatomical Male (CAM) and the Computerized Anatomical Female (CAF), and the resultant early radiation risks were assessed for the blood forming organs (BFO) dose by using the four biomathematical ARS models, which include lymphocytes depression, granulocytes modulation, fatigue and weakness syndrome, and upper gastrointestinal distress. The flow charts of BRYNTRN Organ Dose calculation and Acute Radiation Risk calculation provide an overview of the functions of this web server. Reference:http://spaceradiation.usra.edu/arrbod2/ NSCR2012 V1.0 Web Server Exposure to solar particle events (SPE) and galactic cosmic rays (GCR) poses cancer risks to astronauts. The NASA Johnson Space Center Space Radiation Program Element (JSC-SRPE) has developed cancer risk projection code and has evaluated the level of uncertainty that exists for each of the factors (parameters) that are used in the model. The model originated from recommendations of the National Council on Radiation Protection and Measurements (NCRP, 1997; 2000) with revisions from the latest analysis of human radio-epidemiology data. NASA-defined radiation quality factors are formulated with probability distribution functions (PDFs) to represent uncertainties in leukemia and solid cancer risk estimates. The model was reviewed by the National Research Council (NRC) in 2012. Monte-Carlo propagation of uncertainties from different sources is described with PDFs. Models of the space environment and the BRYNTRN and the HZETRN are used to determine organ exposures behind spacecraft shielding. The purpose of the NASA Space Cancer Risk (NSCR) web server is to provide seamless integration of input and output manipulations, which are required for operation of the sub-modules–BRYNTRN, SUMSHIELD, and the Cancer probabilistic response
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Gap’s in NASA Human Reserach Roadmap models. The main applications envisioned are International Space Station (ISS) missions, and planning for future exploration missions to the moon, near earth objects (NEO), or Mars. In addition, cancer risk estimates for medical diagnostic and aviation radiation exposures are evaluated using similar methods. Reference:http://spaceradiation.usra.edu/nscr/ OLTARIS The On-Line Tool for the Assessment of Radiation in Space (OLTARIS,) is a web-based set of tools and models that allows engineers and scientists to assess the effects of space radiation on spacecraft, habitats, rovers, and spacesuits. The site is intended to be a design tool for those studying the effects of space radiation for current and future missions as well as a research tool for those developing advanced material and shielding concepts. The tools and models are built around the HZETRN2010 radiation transport code and are primarily focused on human and electronic-related responses. Reference:https://oltaris.nasa.gov/
NAIRAS The Nowcast of Atmospheric Ionizing Radiation for Aviation Safety (NAIRAS) is a NASA physics-based prototype operational model for predicting aircraft radiation exposure from galactic and solar cosmic rays. NAIRAS predictions are currently streaming live from the projectŠs public website. The NAIRAS model provides data-driven, global, realtime predictions of atmospheric ionizing radiation exposure rates on a geographic 1x1 degree latitude and longitude grid from the surface of the Earth to 100 km with a vertical resolution of 1 km. The real-time, global predictions are updated every hour. Physics-based models are utilized within NAIRAS to transport cosmic rays through three distinct material media: the heliosphere, Earth’s magnetosphere, and the neutral atmosphere. The physics-based models are input-driven by real-time measurement data. An initial validation of the NAIRAS model has been conducted by comparing with reference aircraft radiation measurement data and with recent aircraft measurements provided by the German Aerospace Corporation. Further validation studies will be performed via the NASA Radiation Dosimetry Experiment (RaD-X) balloon flight mission, which is scheduled to launch in 2015. The Automated Radiation Measurements for Aviation Safety (ARMAS) project, led by Space Environment Technologies, is developing the technology to improve the NAIRAS model with real-time aircraft radiation measurements using data assimilation methods. Reference:http://sol.spacenvironment.net/ñairas/index.html HemoDose Web Tools After the events of September 11, 2001 and recent events at the Fukushima reactors in Japan, there is an increasing concern of the occurrence of nuclear and radiological terrorism or accidents that may result in large casualty in densely populated areas. To guide medical personnel in their clinical decisions for effective medical management and treatment of the exposed individuals, biological markers are usually applied to examine the radiation induced changes at different biological levels. Among these the peripheral blood cell counts are widely used to assess the extent of radiation induced injury. This is due to the fact that hematopoietic system is the most vulnerable part of the human body to radiation damage. Particularly, the lymphocyte, granulocyte, and platelet cells are the most radiosensitive of the blood elements, and monitoring their changes after exposure is regarded as the most practical and best laboratory test to estimate radiation dose. The HemoDose web tools are built upon solid physiological and pathophysiological understanding of mammalian hematopoietic systems, and rigorous coarse-grained bio-mathematical modeling and validation. Using single or serial granulocyte, lymphocyte, leukocyte, or platelet counts after exposure, these tools can estimate absorbed doses of adult victims very rapidly and accurately. Some patient data in historical accidents are utilized as examples to demonstrate the capabilities of these tools as a rapid point-of-care diagnostic or centralized high-throughput assay system in a large scale radiological disaster scenario. Unlike previous dose prediction algorithms, the HemoDose web tools establish robust correlations between the absorbed doses and victim’s various types of blood cell counts not only in the early time window (1 or 2 days), but also in very late phase (up to 4 weeks) after exposure. Reference:http://spaceradiation.usra.edu/hemodose/
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R EFERENCES 1.SAMPEX Data Center. Available online at http://www.srl.caltech.edu/sampex/DataCenter/index.html. 2. SPENVIS,ESA’s Space Environment Information System. Available online at https://www.spenvis.oma.be/. 3.Astronaut EVA exposure estimates from CAD model spacesuit geometry.De Angelis G, Anderson BM, Atwell W, Nealy JE, Qualls GD, Wilson JW. J Radiat Res. 2004 Mar;45(1):1-9.PMID: 15133283 . 4.Analysis of a Radiation Model of the Shuttle Space Suit,NASA/TP-2003-212158. Available online(http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20030033907.pdf) 5.V.M. Petrov, D.A. Kartashov, Yu.A. Akatov, A.V. Kolomensky, V.A. Shurshakov, Comparison of space radiation doses inside the Matroshka-torso phantom installed outside the ISS with the doses in a cosmonaut body in Orlan-M spacesuit during EVA, Acta Astronautica, Volume 68, Issues 9-10, May-June 2011, Pages 1448-1453, ISSN 0094-5765, http://dx.doi.org/10.1016/j.actaastro.2010.06.002. 6.Construction of boundary-surface-based Chinese female astronaut computational phantom and proton dose estimation. Sun W, Jia X, Xie T, Xu F, Liu Q. J Radiat Res. 2013 Mar 1;54(2):383-97. doi: 10.1093/jrr/rrs100. Epub 2012 Nov 7. PMID: 23135158 7.T.P. Dachev, J.V. Semkova, B.T. Tomov, Yu.N. Matviichuk, P.G. Dimitrov, R.T. Koleva, St. Malchev, N.G. Bankov, V.A. Shurshakov, V.V. Benghin, E.N. Yarmanova, O.A. Ivanova, D.-P. Häder, M. Lebert, M.T. Schuster, G. Reitz, G. Horneck, Y. Uchihori, H. Kitamura, O. Ploc, J. Cubancak, I. Nikolaev, Overview of the Liulin type instruments for space radiation measurement and their scientific results, Life Sciences in Space Research, Volume 4, January 2015, Pages 92-114, ISSN 2214-5524, http://dx.doi.org/10.1016/j.lssr.2015.01.005. 8.G.S. Krigsfeld, J.B. Shah, J.K. Sanzari, L. Lin, A.R. Kennedy, Evidence of disseminated intravascular coagulation in a porcine model following radiation exposure, Life Sciences in Space Research, Volume 3, October 2014, Pages 1-9, ISSN 2214-5524, http://dx.doi.org/10.1016/j.lssr.2014.07.001. 9.S.K. Aghara, S.I. Sriprisan, R.C. Singleterry, T. Sato, Shielding evaluation for solar particle events using MCNPX, PHITS and OLTARIS codes, Life Sciences in Space Research, Volume 4, January 2015, Pages 79-91, ISSN 2214-5524, http://dx.doi.org/10.1016/j.lssr.2014.12.003. 10.John W. Wilson, Tony C. Slaba, Francis F. Badavi, Brandon D. Reddell, Amir A. Bahadori, 3DHZETRN: Shielded ICRU spherical phantom, Life Sciences in Space Research, Volume 4, January 2015, Pages 46-61, ISSN 2214-5524, http://dx.doi.org/10.1016/j.lssr.2015.01.002. 11.The MATROSHKA Experiment: Results and Comparison from Extravehicular Activity (MTR-1) and Intravehicular Activity (MTR-2A/2B) Exposure Thomas Berger, Pawel Bilski, Michael Hajek, Monika Puchalska, and Günther Reitz Radiation Research 2013 180 (6), 622-637. 12.Hajek M, Berger T, Fugger M, Fürstner M, Vana N, Akatov Y, Shurshakov V, Arkhangelsky V. Dose distribution in the Russian Segment of the International Space Station. Radiat Prot Dosimetry. 2006;120(1-4):446-9. Epub 2006 Apr 10.PubMed PMID: 16606660. 13.Edward Semones, CHP,Passive Dosimetry: Area and Crew Monitoring,NCRP Review of NASA Space Radiation Operations,NASA. 14.Smith, D. S., and J. M. Scalo (2007), Risks due to X-ray flares during astronaut extravehicular activity, Space Weather, 5, S06004, doi:10.1029/2006SW000300. 15.Radiation Protection Studies of International Space Station Extravehicular Activity Space Suits,NASA/TP-2003-212051.
16.Cucinotta, Francis A. "Space radiation organ doses for astronauts on past and future missions." (2007). ISOPTWPO Today Page 36 International Space Agency(ISA)
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17.Cucinotta FA (2014) Space Radiation Risks for Astronauts on Multiple International Space Station Missions. PLoS ONE 9(4): e96099. doi:10.1371/journal.pone.0096099. 18.AE8/AP8 IMPLEMENTATIONS IN AE9/AP9, IRBEM, AND SPENVIS,AFRL-RV-PSTR-2014-0014. 19.ICRP, 2013. Assessment of Radiation Exposure of Astronauts in Space. ICRP Publication 123. Ann. ICRP 42(4). 20.Francis F. Badavi,Status of the of Trapped Model AE9/AP9/SPM (IRENE) for the ISS Environment,WRMISS19, 911 September 2014, Krakow, Poland. (http://wrmiss.org/workshops/nineteenth/Badavi.pdf). 21.Francis F. Badavi,Estimates of Cosmic Rays Directional Dose for ISS,WRMISS18, 3-5 September 2013, Budapest, Hungary. (http://wrmiss.org/workshops/eighteenth/Badavi_GCR.pdf). 22.Francis F. Badavi,Evaluation of the New Trapped Proton Model (AP9) at ISS Attitudes,WRMISS18, 3-5 September 2013, Budapest, Hungary. (http://wrmiss.org/workshops/eighteenth/Badavi_Introduction.pdf). 23.EuCPAD - European Crew Personal Active Dosemeter: Development Status,18th WRMISS, Budapest, Hungary 03 05 September, 2013. (http://wrmiss.org/workshops/eighteenth/Berger_EuCPAD.pdf). 24.Thomas Berger and Günther Reitz,The MATROSHKA Facility - Dose determination during an EVA,DLR. (http://wrmiss.org/workshops/ninth/radiation/berger.pdf). 25.Soenke Burmeister, Thomas Berger, Johannes Labrenz, Matthias Boehme, Lutz Haumann,Guenther Reitz,Long Term Dose Monitoring Onboard the European Columbus Module of the International space Station in the frame of the DOSIS and DOSIS 3D Project- Results from the active Instruments. (http://wrmiss.org/workshops/nineteenth/Burmeister.pdf). 26.A.S. Johnson, M.J. Golightly, M.D. Weyland, T. Lin, E.N. Zapp, Minimizing space radiation exposure during extravehicular activity, Advances in Space Research, Volume 36, Issue 12, 2005, Pages 2524-2529, ISSN 0273-1177, http://dx.doi.org/10.1016/j.asr.2004.05.008. 27.D. A. Kartashov, V. A. Shurshakov, and A. V. Kolomenskii,Optimization of Radiation Exposures during Extravehicular Activity Using the Effect of the West-East Asymmetry of the Fluxes of Trapped Protons,ISSN 0010-9525, Cosmic Research, 2011, Vol. 49, No. 6, pp. 504-509. 28.Brittingham, John Macdougall, "Development of a FLUKA-Based Lookup Tool for Rapid Analysis of Radiation Exposures in Space Environments. " PhD diss., University of Tennessee, 2014.http://trace.tennessee.edu/utk_graddiss/2681. 29.OSCAR LARSSON,Analysis of the Radiation Environment on Board the International Space Station Using Data from the SilEye-3/Alteino Experiment,Doctoral Thesis,Stockholm, Sweden 2014. 30.M. Hajek, T. Berger, N. Vana, M. Fugger, J.K. Pálfalvi, J. Szabó, I. Eördögh, Y.A. Akatov, V.V. Arkhangelsky, V.A. Shurshakov, Convolution of TLD and SSNTD measurements during the BRADOS-1 experiment onboard ISS (2001), Radiation Measurements, Volume 43, Issue 7, August 2008, Pages 1231-1236, ISSN 1350-4487, http://dx.doi.org/10.1016/j.radmeas.2008.04.094.
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ISOPTWPO The International Space Agency (ISA) was founded by Mr. Rick Dobson, Jr., a U.S. Navy Veteran, and established as a non-profit corporation for the purpose of advancing Man’s visionary quest to journey to other planets and the stars. ISOPTWPO(International Space Flight & Operations - Personnel Recruitment, Training, Welfare, Protocol Programs Office) is part of ISA, which support research on Human Space Flight and its complications. ISOPTWPO will research on NASA’S Human Research Roadmap. It will also research on long duration spaceflight and publish special issues on one year mission at ISS and twin study. Mr. Martin Cabaniss is director and Mr. Abhishek Kumar Sinha is Assistant Director of ISOPTWPO. Ad Astra ! To The Stars! In Peace For All Mankind ! Mr. Rick R. Dobson, Jr.(Veteran U.S Navy) — International Space Agency (ISA)
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